Emergency Instructions:220 V DC Failure



220 V DC Failure
Unit condition
Ø  DCDB section-1 & 2 under voltage alarm in LVS-5
Ø  All HT/LT Breakers Indication Becomes Bad
Ø  Boiler will Trip on MFT ( after 2 Sec)
Ø  Turbine will Trip on MFT
Ø  Generator will not Trip as GCB Protection will not act
Ø  Generator will run as Synchronous Motor
Ø  HP/IP/LP Casing Exhaust Temperature will start increasing
Ø  400 KV Breakers can be Operable
Ø  Feeders of Mill will Trip on MFT
Ø  Fans(ID, FD, PA), Mills, BCW Pumps etc will continue to run
Ø  DC Drives can not come in service
Actions
Ø  Sequence to Trip Drives:
·         PA fan
·         Mills
·         One set ID/FD
·         Another set of ID/FD
·         BCW Pumps
·         MDFP
·         CEP
·         SG ECW
·         TG ECW
·         Air compressors
·         CW Pumps
Ø  Start DG set
Ø  Start AOP-1, SOP-1, AOP-1 of TDBFPs, PW-1
Ø  Trip Normal Incomer breaker from unit service Board to Emergency board from Switchgear
Ø  Close DG set incomer breaker to emergency Board from Switchgear
Ø  Start AOP-2, SOP-2, AOP-2 of TDBFPs, PW-2
Ø  Trip 400 KV Main/Tie GCB from CCR/Switchyard
Ø  Trip Station Transformer after shifting critical equipments
Ø  This will result in Total Power Failure with Emergency Board in charged condition

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